1. Field of the Invention
The present invention relates to the field of optical fiber cables and especially to the reinforcement structures of such cables and fibers.
Optical fibers used for telecommunications by optical signals are elements based on silicates (glass or quartz) that are particularly brittle and poorly withstand weight, tensile and compressive forces. There are known ways of using reinforcement structures to form an optical fiber cable designed to cover long-haul and short-haul communications.
2. Description of the Prior Art
The patent FR-A-2 728 694 filed on behalf of the present Applicant teaches an elementary reinforcement structure in which at least one optical fiber is inserted into a rigid shell called a microcarrier to form an optical module (also called a micromodule) that is reinforced in order to limit the curvature of the fiber and the attenuation of the optical signals.
The patent application No. FR-A 2 747 201 filed on behalf of the present Applicant teaches a more evolved structure in which optical modules (micromodules) are associated with rigid reinforcement modules (micro-reinforcements) and molded in a polymer sheath to form a cable. The application describes essentially flat cables in which the micromodules and the micro-reinforcements are coplanar, the sheathed cable having the form of a ribbon.
The documents DE-A1-32 32 108, EP-A2-0 328 409, EP-B1-0428036 describe other structures of reinforced cables with coplanar optical modules.
The known cables have the drawback of high rigidity related to the structures designed to withstand compressive and tensile strains.
Another drawback specific to cable structures in ribbon form is that they get twisted on curved paths with small radius.
Such drawbacks rule out domestic applications as domestic cables have to withstand specific mechanical strains due to the low radii of curvature in the boxes, internal wiring systems, thermal shock and overhead wiring with elongation.